The present invention relates generally to microscopy, more specifically to phase contrast microscopy, and, even more particularly, to a multiple phase contrast annulus slider for a microscope.
As is well known, a microscope is an optical instrument used to view, examine and study very small objects. There are many different types of microscopes, each best suited to particular applications. These include compound microscopes, stereomicroscopes, confocal microscopes, inverted microscopes, laser microscopes, fluorescence microscopes and polarizing microscopes, to name but a few.
The present invention relates generally to compound microscopes and to those compound microscopes that are equipped to carry out phase contrast microscopy.
A variety of removable components are frequently used with compound microscopes to illuminate the object being investigated with diverse types of light. Components of this type include phase rings that create phase shifts in the light illuminating an object being investigated. Phase shifts of this type take advantage of differential diffraction of light as it passes through transparent objects such as single cell organisms to allow objects under study that are invisible under bright field conditions to become visible to the microscope user. This form of microscopy is called phase contrast microscopy.
It is well known in the art that in phase contrast microscopy, a pair of phase rings is used to create the phase shift. One ring is usually positioned within the microscope objective at the image plane near the nosepiece, while the other phase ring, commonly called a phase contrast annulus or simply, an annulus, is placed between the light source and the condenser. For each microscope objective having a different magnification, a different phase ring/annulus pair must be placed into the light path.
Because the phase rings located on a phase contrast objective are permanently positioned so as to be to be automatically brought into proper alignment in the illumination beam path, there is no difficulty in always selecting the correct objective phase ring for the desired magnification. However, one difficulty created by the necessity of using different pairs of phase rings for different magnifications is the need to change the phase contrast annulus positioned between the light source and the condenser. Because the phase contrast annulus is positioned underneath the microscope stage, it is awkward to determine if the correct annulus is being used for a particular magnification.
An additional problem in using phase contrast microscopes is that the phase ring/annulus pair must be changed with each change in magnification. The phase ring is automatically correctly switched when the desired objective is placed into position. However, the annulus is commonly changed by inserting into and removing from the condenser components that hold a single annulus appropriate for the desired magnification. This results in unused phase contrast annuli being exposed in a loose manner at a work station where they can be easily lost or damaged. This is especially true in educational settings in which the user may be an inexperienced student who may be performing a variety of exercises requiring an array of different phase rings in a limited period of time. This problem can also exist in a clinical setting where different tests and procedures may require frequent changes of phase contrast annuli as different magnifications are used. Alternatively, phase contrast annuli may be mounted on a turret attached to a microscope condenser which allows the user to turn the phase ring into position. However, such turret-condenser assemblies are expensive and require a final adjustment of the annulus after it is turned in order to align the annulus with the objective phase contrast ring.
Others have disclosed sliders for supporting and positioning components into the illumination path of a compound microscope. Sliders currently exist that either hold two phase contrast annuli or hold a single phase contrast annulus and define a bright field aperture. In addition, U.S. Pat. No. 4,756,611 to Yonekubo, et al. discloses a turret having multiple phase contrast annuli as well as other light altering elements commonly used in light microscopy. U.S. Pat. No. 4,807,980 to Dietrich discloses a condenser with an element that pivots a light filter or similar element into the illumination path of a compound microscope. Only one element is contained in the pivot arm of the ""980 patent. U.S. Pat. No. 5,032,011 to Muchel describes a condenser possessing a space that can accept a slider or a turret containing phase contrast rings or other light microscopy components. U.S. Pat. No. 5,371,624 to Nagono, et al. discloses a slider defining a bright field opening and holding two equal size fluorescent light filters used in fluorescent microscopy.
None of the above disclosures depict a slider possessing phase contrast annuli for all objectives commonly found on phase contrast microscopes. What is needed then is a device that is capable of holding phase contrast annuli for low, medium and high magnifications typically found on a compound microscope in an educational or clinical setting. Preferably, such a slider will be of such a length as to not extend beyond the outline of the microscope stage while still holding three phase contrast annuli as well as a bright field aperture. In addition, there is a need for a mechanism for removably securing a slider in the condenser while still allowing it to slide freely to position the desired annulus into proper alignment in the illumination beam path.
The present invention broadly comprises a device, such as a slider, for performing phase contrast microscopy, the device containing a plurality of at least three phase contrast annuli. The device is received into a microscope condenser mounted under a microscope stage and that is adapted to receive the device and align one of the phase contrast annuli with the appropriate objective phase ring without the need for a final alignment.
The invention also comprises printed or engraved indicators or other markings indicating whether the bright field aperture or a particular phase contrast annulus is in position in the illumination path of the microscope. The invention further comprises a mechanism for preventing the removal of the device from the condenser.
A general object of the invention is to provide a device, such as a slider, capable of holding a plurality of at least three phase contrast annuli in addition to a bright field aperture.
A second object of the invention is to provide a device capable of holding a bright field aperture with a plurality of at least three phase contrast annuli.
An additional object of the invention is to provide a device having a handle to enable easy movement of the device within the condenser.
An additional object of the invention is to disclose a device with indicia designating whether a bright field aperture or one of a plurality of phase contrast annuli is positioned in the illumination path of the microscope.
A further object of the invention is to disclose a component designed to prevent the device from being removed from the condenser of a compound microscope.
A further object of the invention is to provide a device configured to correctly align a phase contrast annulus contained on the device with an appropriate objective phase ring without the use of a final alignment.
A still further object of the invention is to minimize the area on a device, such as a slider, needed to hold a plurality of phase contrast annuli.